JP7270035B2 - Diene rubber and rubber composition - Google Patents

Description

The present invention relates to a diene rubber, a rubber composition containing the diene rubber, a crosslinked product containing the rubber composition, a tire tread, a bead filler, and a tire belt using at least a part of the rubber composition or the crosslinked product. and pneumatic tires. The present invention also relates to a resin modifier comprising the diene rubber.

Pneumatic tires, especially all-season tires, winter tires, and studless tires, have not only mechanical properties such as wear resistance, hardness, and strength, but also grip performance on wet roads (wet grip performance), It is desired that the grip performance (ice grip performance) and the like are also at a high level.

Increasing Tan δ (hysteresis loss) is effective in improving wet grip performance. However, if an additive such as a resin is blended to increase Tan δ, there is a problem that the flexibility of the rubber is lowered.
In order to improve the ice grip performance, it is effective to increase the contact area between the tire and ice and snow, and to improve the flexibility of the tire at low temperatures. As a method for imparting flexibility to tires, there are a method of using a solid rubber with a low glass transition temperature (Tg), a method of reducing the amount of carbon black, and an average particle size of about 100 to 200 nm of the carbon black to be blended. and a method of blending a softening agent such as oil. However, when the ice grip performance of the tire is improved by imparting flexibility, there is a problem that the wet grip performance is lowered. In addition, when a softening agent such as oil is blended, over time, these will bleed out of the compound, causing the rubber to harden over time. There is also the problem of lowering

In addition, generally, in order to improve the mechanical properties of the obtained rubber composition or the crosslinked product of the rubber composition, a method of compounding a filler such as carbon black or silica into the rubber composition as a rubber reinforcing agent is known. ing. However, this method has a problem that workability during production is lowered. Therefore, process oils, liquid polymers, and the like are used as workability improvers. However, when a conventional workability improver is used, although workability is improved, there is a problem that both ice grip performance and wet grip performance cannot be achieved at a high level.

Patent Document 1 describes a rubber composition containing a coumarone-indene resin having a softening point of 50° C. or less, and describes that ice grip performance and abrasion resistance can be improved in a well-balanced manner. In Patent Document 2, a styrene-butadiene rubber having a specific bound styrene content and a vinyl content, a low-molecular-weight butadiene rubber having a specific cis-1,4-structure content and a weight-average molecular weight, and silica are mixed in a specific manner. is described, and it is described that performance on ice and wet grip performance are improved. Patent Document 3 discloses a linear or branched diene elastomer derived from at least one conjugated diene and a reinforcing filler, and wherein the elastomer has a mass content of 15% or more of cyclic vinyl units and 30,000 Compositions with number average molecular weights of ~350,000 g/mol are described and are said to be capable of improving hysteresis loss and tensile modulus.

JP 2013-139522 A JP-A-2002-060549 Japanese Patent Publication No. 2006-515897

However, although the rubber compositions described in Patent Documents 1 to 3 have improved wear resistance and various braking performances compared to conventional ones, they are still insufficient in terms of both ice grip performance and wet grip performance. Further improvements are desired.

The present invention has been made in view of the above-mentioned current situation, and a diene rubber that can provide a crosslinked product or a rubber composition having both ice grip performance and wet grip performance at a high level, and a rubber containing the diene rubber An object of the present invention is to provide a composition, a tire member comprising the rubber composition or a crosslinked product of the rubber composition, and a tire at least partly using the rubber composition or the crosslinked product of the rubber composition. Another object of the present invention is to provide a resin modifier comprising a diene rubber capable of giving a resin composition having the above properties.

As a result of intensive studies by the present inventors, it was found that by including a diene rubber or the like having a specific relatively small molecular weight in a rubber composition, the rubber composition or a crosslinked product of the rubber composition has a wet grip. The present inventors have found that the diene rubber is useful as a resin modifier, and have completed the present invention.

That is, the present invention relates to [1] to [12] below.
[1] A diene rubber (A) containing a butadiene unit having a weight average molecular weight of 5,000 to 50,000,
β _{is 12} mol%, and β _cp mol% is the mol% of the structural unit represented by the following formula (1), based on the total butadiene units contained in the diene rubber (A). A diene rubber (A) that satisfies the following (i) to (iii) when
(i) β _cp >0
(ii) β ₁₂ >40
(iii) _βcp /( _β12-40 )≤2

〔２〕〔１〕に記載のジエン系ゴム（Ａ）を含有するゴム組成物。
〔３〕さらに固形ゴム（Ｂ）を含有する〔２〕に記載のゴム組成物。
〔４〕さらにフィラー（Ｃ）を含有する〔２〕又は〔３〕に記載のゴム組成物。
〔５〕〔２〕～〔４〕のいずれかに記載のゴム組成物を架橋させた架橋物。
〔６〕〔２〕～〔４〕のいずれかに記載のゴム組成物又は〔５〕に記載の架橋物を少なくとも一部に用いたタイヤトレッド。
〔７〕〔２〕～〔４〕のいずれかに記載のゴム組成物又は〔５〕に記載の架橋物を少なくとも一部に用いたビードフィラー。
〔８〕〔２〕～〔４〕のいずれかに記載のゴム組成物又は〔５〕に記載の架橋物を少なくとも一部に用いたタイヤ用ベルト。
〔９〕〔２〕～〔４〕のいずれかに記載のゴム組成物又は〔５〕に記載の架橋物を少なくとも一部に用いた空気入りタイヤ。
〔１０〕前記空気入りタイヤがウインタータイヤ又はスタッドレスタイヤである、〔９〕に記載の空気入りタイヤ。
〔１１〕前記空気入りタイヤがオールシーズンタイヤである、〔９〕に記載の空気入りタイヤ。
〔１２〕〔１〕に記載のジエン系ゴム（Ａ）からなる樹脂改質剤。

[2] A rubber composition containing the diene rubber (A) described in [1].
[3] The rubber composition according to [2], which further contains a solid rubber (B).
[4] The rubber composition according to [2] or [3], which further contains a filler (C).
[5] A crosslinked product obtained by crosslinking the rubber composition according to any one of [2] to [4].
[6] A tire tread at least partially using the rubber composition according to any one of [2] to [4] or the crosslinked product according to [5].
[7] A bead filler at least partially using the rubber composition according to any one of [2] to [4] or the crosslinked product according to [5].
[8] A tire belt at least partially using the rubber composition according to any one of [2] to [4] or the crosslinked product according to [5].
[9] A pneumatic tire at least partially using the rubber composition according to any one of [2] to [4] or the crosslinked product according to [5].
[10] The pneumatic tire according to [9], wherein the pneumatic tire is a winter tire or a studless tire.
[11] The pneumatic tire according to [9], wherein the pneumatic tire is an all-season tire.
[12] A resin modifier comprising the diene rubber (A) described in [1].

By including the diene rubber obtained by the present invention as one component of the rubber composition, the rubber composition or the crosslinked product of the rubber composition has both wet grip performance and ice grip performance at a high level. Therefore, materials partially using the rubber composition or the crosslinked product are useful as tire treads, bead fillers, tire belts, and pneumatic tires. Moreover, since the resin composition containing the diene rubber has the above properties, the diene rubber can be used as a resin modifier.

[Diene rubber (A)]
The diene rubber (A) of the present invention is a low molecular weight polymer having a weight average molecular weight (Mw) in the range of 5,000 to 50,000, containing butadiene units, When the mol% of the 1,2-bonded butadiene units is β ₁₂ mol% and the mol% of the structural units represented by the above formula (1) is _cp mol%, the following Those that satisfy (i) to (iii).

(i) β _cp >0
(ii) β ₁₂ >40
(iii) _βcp /( _β12-40 )≤2

The weight average molecular weight (Mw) of the diene rubber (A) is in the range of 5,000 to 50,000, preferably 40,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less. Moreover, the weight average molecular weight (Mw) of the diene rubber (A) is preferably 5,500 or more, more preferably 6,000 or more, and even more preferably 6,500 or more. In the present invention, the Mw of the diene rubber (A) is the polystyrene-equivalent weight-average molecular weight obtained from measurement by gel permeation chromatography (GPC). When the Mw of the diene rubber (A) is within the above range, it is excellent in the ability to pass through the manufacturing process and is economically efficient. In addition, processability is improved when producing or using a rubber composition containing a solid rubber (B) or a resin composition containing a resin, which will be described later.

The molecular weight distribution (Mw/Mn) of the diene rubber (A) is preferably 1.0 to 20.0, more preferably 1.0 to 15.0, even more preferably 1.0 to 10.0, and 1.0 ~5.0 is particularly preferred, and 1.0 to 2.0 is most preferred. It is preferable that the Mw/Mn is within the above range because the variation in viscosity of the obtained diene rubber (A) is small. The molecular weight distribution (Mw/Mn) means the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) in terms of standard polystyrene obtained by GPC measurement.

The diene rubber (A) contains a butadiene unit as a monomer unit constituting the polymer. In one embodiment, the diene rubber (A) preferably contains butadiene units in an amount of 50% by mass or more of all the monomer units constituting the polymer. The content of butadiene units is preferably 60 to 100% by mass, more preferably 70 to 100% by mass, based on the total monomer units of the diene rubber (A). The content of butadiene units can be determined in consideration of compatibility with the solid rubber (B). For example, when the solid rubber (B) contains butadiene rubber, isoprene rubber, and natural rubber , the total content of butadiene units is 100% by mass.

Examples of monomer units other than butadiene units that can be contained in the diene rubber (A) include conjugated diene (a1) units other than butadiene, aromatic vinyl compound (a2) units, and the like.

Examples of conjugated dienes (a1) other than butadiene include isoprene, 2,3-dimethylbutadiene, 2-phenylbutadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1 ,3-octadiene, 1,3-cyclohexadiene, 2-methyl-1,3-octadiene, 1,3,7-octatriene, myrcene, and chloroprene. Among these conjugated dienes (a1), isoprene is preferred.

Examples of the aromatic vinyl compound (a2) include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-t-butylstyrene and 4-cyclohexylstyrene. , 4-dodecylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 2,4,6-trimethylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, 1-vinylnaphthalene , 2-vinylnaphthalene, vinylanthracene, N,N-diethyl-4-aminoethylstyrene, vinylpyridine, 4-methoxystyrene, monochlorostyrene, dichlorostyrene, and divinylbenzene. Among these aromatic vinyl compounds, styrene, α-methylstyrene, and 4-methylstyrene are preferred.

The content of monomer units other than butadiene units in the diene rubber (A) is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

The diene rubber (A) contains a structural unit represented by the following formula (1), that is, the structural unit represented by the following formula (1) in mol% (β _cp mol %) must exceed 0 mol % (β _cp >0) (requirement (i)).

By including such a structural unit in the diene rubber (A), in a rubber composition containing the diene rubber (A) and the solid rubber (B), or in a crosslinked product obtained from the rubber composition, ice grip It is possible to achieve both performance and wet grip performance. In order to improve ice grip performance and wet grip performance, β _cp mol % is preferably 0.5 mol % or more (β _cp ≧0.5), and 0.8 mol % or more (β _cp ≧0 .8) is more preferred. Also, β _cp mol % is usually 30 mol % or less (β _cp ≦30). Using ¹ H-NMR, the mol % of the structural unit represented by the above formula (1) is determined by the peak derived from the structural unit represented by the formula (1) and other butadiene units (1,2-bonded butadiene units , 1,4-bonded butadiene units). The mol % (β _cp mol %) of the structural unit represented by the formula (1) of the diene rubber (A) is, for example, the type of solvent used in producing the diene rubber (A), A desired value can be obtained by controlling the polar compound used, the polymerization temperature, the concentration of the monomer (butadiene), and the supply rate when the monomer is continuously or intermittently supplied to the polymerization system. can be done.

The mol % (β ₁₂ mol %) of 1,2-bonded butadiene units with respect to all butadiene units in the diene rubber (A) exceeds 40 mol % (β ₁₂ >40) (requirement (ii)). In a rubber composition using such a diene rubber (A) having such a 1,2-bond content together with a solid rubber (B) or a crosslinked product obtained from the rubber composition, the Tan δ of the rubber composition is increased and wet Excellent grip performance and ice grip performance. From the viewpoint of improving wet grip performance and ice grip performance, β ₁₂ mol% is preferably 42 mol% or more (β ₁₂ ≧42). From the point of view of (handleability), β ₁₂ mol % is preferably 80 mol % or less (β ₁₂ ≦80), more preferably 70 mol % or less (β ₁₂ ≦70). The mol % of 1,2-bonded butadiene units is determined by using ¹ H-NMR, peaks derived from 1,2-bonded butadiene units and other butadiene units (1,4-bonded butadiene units, the above formula It can be calculated from the area ratio with the peak derived from (structural unit represented by (1)). The 1,2-bond butadiene unit mol% (β ₁₂ mol%) of the diene rubber (A) is, for example, the type of solvent used in producing the diene rubber (A), A desired value can be obtained by controlling the polar compound used in the process, the polymerization temperature, and the like.

In the diene rubber (A), β ₁₂ mol % and β _cp mol % must further satisfy the condition of β _cp /(β ₁₂ -40)≦2 (requirement (iii)).
As described above, by increasing the mol% of 1,2-bonds in the butadiene unit contained in the diene rubber (A) (for example, exceeding 40 mol%), the Tg of the liquid rubber is increased, and the compounded rubber composition Ice grip performance and wet grip performance can be improved by increasing the Tg of the object). However, in order to improve the ice grip performance and wet grip performance of the crosslinked product of the rubber composition containing the solid rubber (B) and the low-molecular-weight diene-based rubber, the wide temperature range of -20°C to 30°C , its Tan δ value needs to be improved. It is difficult to improve the Tan δ of the crosslinked product over this wide temperature range only by increasing the mol % of 1,2-bonds in the diene rubber. Therefore, it is important that the diene rubber (A) contains the structural unit represented by the above formula (1). On the other hand, when a large amount of the structure of formula (1) is contained in the diene rubber (A), the elastic modulus of the crosslinked product obtained from the rubber composition containing the diene rubber (A) and the solid rubber (B) is It becomes too high, and it is difficult to obtain a crosslinked product having the desired flexibility, hardness, etc. expected from the properties of the solid rubber (B). According to the studies of the present inventors, in order to obtain a crosslinked product having desired physical properties such as flexibility and hardness while improving ice grip performance and wet grip performance, the formula (1) It has been found that the ratio between the mol % of structural units of and the mol % of 1,2-bonds above 40% is important. When the mole % of 1,2-bonds relative to the mole % of structural units of formula (1) in the diene rubber (A) increases, cross-linking of the rubber composition comprising the diene rubber (A) and the solid rubber (B) When performing the above, the speed of cross-linking of the diene rubber (A) increases, and a cross-linked product having a higher degree of cross-linking tends to be easily obtained. On the other hand, the structural unit of formula (1) is a structural unit capable of achieving the highest glass transition temperature among structural units derived from butadiene, but it also has a structure that is less likely to be crosslinked than other butadiene units. By keeping the ratio of these two structures within a specific range, the Tan δ value can be improved over a wide temperature range of -20°C to 30°C while maintaining an appropriate degree of cross-linking. It is estimated that

β _cp /(β ₁₂ -40) should be 1.8 or less (β _cp /(β ₁₂ -40) ≤ 1.8) from the viewpoint of further improving ice grip performance and wet grip performance of the resulting crosslinked product. is preferably 1.5 or less (β _cp /(β ₁₂ -40) ≤ 1.5), more preferably 0.7 or less (β _cp /(β ₁₂ -40) ≤ 0.7) is particularly preferred, and β _cp /(β ₁₂ -40) is most preferably 0.4 or less (β _cp /(β ₁₂ -40)≦0.4).

The melt viscosity of the diene rubber (A) measured at 38° C. is preferably 0.1 to 2,000 Pa·s, more preferably 0.1 to 1500 Pa·s, and even more preferably 0.1 to 1000 Pa·s. 0.1 to 500 Pa·s is more preferred, 0.1 to 250 Pa·s is particularly preferred, 0.1 to 100 Pa·s is even more preferred, and 0.1 to 50 Pa·s is most preferred. When the melt viscosity of the diene rubber (A) is within the above range, when used as a rubber composition together with the solid rubber (B) described later, the flexibility of the resulting rubber composition is improved, resulting in improved processability. do. The melt viscosity of the diene rubber (A) can be set to a desired value, for example, by controlling Mw and Mw/Mn of the diene rubber (A). In the present invention, the melt viscosity of the diene rubber (A) is a value measured at 38°C with a Brookfield viscometer.

The Tg of the diene rubber (A) is preferably 0°C or lower. Tg is derived from mol % of butadiene units and 1,2-bonds (and 3,4-bonds) in conjugated diene (a1) units other than butadiene, type of conjugated diene (a1), and monomers other than conjugated dienes. Although it may change depending on the content of the unit, from the viewpoint of abrasion resistance, ice grip performance, and rolling resistance performance, -10 ° C. or less is more preferable, -20 ° C. or less is more preferable, and -30 ° C. or less is even more preferable. , -40°C or lower is particularly preferred, -50°C or lower is more preferred, -60°C or lower is most preferred, and -70°C or lower is most preferred. The Tg of the diene rubber (A) is preferably −100° C. or higher, more preferably −90° C. or higher, further preferably −70° C. or higher, from the viewpoint of steering stability performance, dry grip performance, and wet grip performance. 60° C. or higher is more preferred, −40° C. or higher is particularly preferred, and −20° C. or higher is most preferred.

The diene rubber (A) is obtained by polymerizing butadiene and optionally other monomers other than butadiene by, for example, an emulsion polymerization method or a solution polymerization method.

As the emulsion polymerization method, a known method or a known method can be applied. For example, a monomer containing a predetermined amount of conjugated diene is emulsified and dispersed in the presence of an emulsifier, and emulsion polymerized with a radical polymerization initiator.

Examples of emulsifiers include salts of long-chain fatty acids having 10 or more carbon atoms and rosinates. Examples of long-chain fatty acid salts include potassium salts or sodium salts of fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, oleic acid and stearic acid.

Water is usually used as the dispersion medium, and it may contain a water-soluble organic solvent such as methanol or ethanol as long as the stability during polymerization is not impaired.
Examples of radical polymerization initiators include persulfates such as ammonium persulfate and potassium persulfate, organic peroxides, and hydrogen peroxide.

A chain transfer agent may be used to adjust the molecular weight of the resulting diene rubber (A). Examples of chain transfer agents include mercaptans such as t-dodecylmercaptan and n-dodecylmercaptan; carbon tetrachloride, thioglycolic acid, diterpene, terpinolene, γ-terpinene, and α-methylstyrene dimer.

The temperature for emulsion polymerization can be appropriately set depending on the type of radical polymerization initiator to be used, etc., but it is usually in the range of 0 to 100°C, preferably in the range of 0 to 60°C. The polymerization mode may be either continuous polymerization or batch polymerization.

Polymerization reactions can be terminated by the addition of a polymerization terminating agent. Examples of the polymerization terminator include amine compounds such as isopropylhydroxylamine, diethylhydroxylamine and hydroxylamine, quinone compounds such as hydroquinone and benzoquinone, and sodium nitrite.

After termination of the polymerization reaction, an anti-aging agent may be added as necessary. After stopping the polymerization reaction, unreacted monomers are removed from the obtained latex if necessary, and then salts such as sodium chloride, calcium chloride and potassium chloride are used as coagulants, and if necessary nitric acid, sulfuric acid and the like are added. After the diene rubber (A) is coagulated while adjusting the pH of the coagulation system to a predetermined value by adding an acid, the polymer is recovered by separating the dispersion medium. Then, the diene rubber (A) is obtained by washing with water, dehydration, and drying. At the time of coagulation, if necessary, the latex and the extender oil made into an emulsified dispersion may be mixed in advance and recovered as an oil-extended diene rubber (A).

As the solution polymerization method, a known method or a known method can be applied. For example, in a solvent, a Ziegler-based catalyst, a metallocene-based catalyst, an anionically polymerizable active metal or active metal compound is used to polymerize a monomer containing a conjugated diene optionally in the presence of a polar compound. .

Examples of solvents include aliphatic hydrocarbons such as n-butane, n-pentane, isopentane, n-hexane, n-heptane and isooctane; alicyclic hydrocarbons such as cyclopentane, cyclohexane and methylcyclopentane; Aromatic hydrocarbons such as toluene and xylene can be mentioned.

Examples of anionically polymerizable active metals include alkali metals such as lithium, sodium and potassium; alkaline earth metals such as beryllium, magnesium, calcium, strontium and barium; and lanthanoid rare earth metals such as lanthanum and neodymium. Among the anionically polymerizable active metals, alkali metals and alkaline earth metals are preferred, and alkali metals are more preferred.

Organic alkali metal compounds are preferred as the anionically polymerizable active metal compound. Examples of organic alkali metal compounds include organic monolithium compounds such as methyllithium, ethyllithium, n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, and stilbenelithium; , 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene; and sodium naphthalene and potassium naphthalene. Among these organic alkali metal compounds, organic lithium compounds are preferred, and organic monolithium compounds are more preferred.

The amount of the organic alkali metal compound to be used can be appropriately set according to the melt viscosity, molecular weight, etc. of the diene rubber (A). Used in parts by weight amounts.

The organic alkali metal compound can also be used as an organic alkali metal amide by reacting it with a secondary amine such as dibutylamine, dihexylamine or dibenzylamine.

In anionic polymerization, the polar compound usually does not deactivate the reaction, and the microstructure of the conjugated diene unit (e.g., 1,2-bonded butadiene unit, 1,4-bonded butadiene unit, or represented by formula (1) used to prepare vinylcyclopentane (VCP) structures). Examples of polar compounds include ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, 2,2-di(2-tetrahydrofuryl)propane (DTHFP); ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether. glycol ethers such as triethylamine, N,N,N',N'-tetramethylenediamine, N,N,N',N'-tetramethylethylenediamine (TMEDA), N-methylmorpholine and other amines; sodium t - sodium or potassium salts of fatty alcohols such as butyrate, sodium t-amylate or sodium isopentylate, or sodium or potassium salts of cycloaliphatic alcohols such as dialkyl sodium cyclohexanolate, e.g. sodium mentholate metal salts. These polar compounds can be used singly or in combination of two or more. The polar compound is generally used in an amount of 0.01 to 1000 mol per 1 mol of the organic alkali metal compound (polymerization initiator). Also, in order to make it easier for β ₁₂ mol% (mol% of 1,2-bonded butadiene units) to be in the desired range that satisfies at least requirement (ii), the polar compound should be preferably in an amount of 0.1 to 1000 mol, more preferably in an amount of 0.1 to 2 mol, still more preferably in an amount of 0.1 to 1 mol, even more preferably in an amount of 0.1 to 0.9 mol used in quantity.

In order to reduce β _cp mol % (mol % of the structural unit represented by the above formula (1)) and at least satisfy the above (iii), the monomer is fed as a monomer during anionic polymerization. It is preferable not to deplete the polymerization system during the process, and it is more preferable to sequentially feed the monomers until all the monomers have been fed. In the case of sequential feeding, the butadiene feed rate is preferably 0.1 mol/min or more, more preferably 0.3 mol/min or more, and more preferably 0.5 mol/min with respect to 1 mol of the initiator. / minute or more is more preferable. Further, from the viewpoint of ease of control of the polymerization temperature during anionic polymerization, in the case of sequential feeding, the feed rate of butadiene with respect to 1 mol of the initiator is preferably 50 mol/min or less, and 10 mol. / minute or less is more preferable.

The temperature of the solution polymerization is usually in the range of -80 to 150°C, preferably in the range of 0 to 100°C, more preferably in the range of 10 to 90°C. The mode of polymerization may be either a batchwise system or a continuous system.

Polymerization reactions can be terminated by the addition of a polymerization terminating agent. Examples of the polymerization terminator include alcohols such as methanol and isopropanol. The resulting polymerization reaction solution is poured into a poor solvent such as methanol to precipitate the diene rubber (A), or the polymerization reaction solution is washed with water, separated, and dried to form the diene rubber (A). It can be isolated.
Among the above methods, the solution polymerization method is preferable as the method for producing the diene rubber (A).

The diene rubber (A) preferably has a catalyst residue amount derived from the polymerization catalyst used for its production in the range of 0 to 200 ppm in terms of metal. For example, when an organic alkali metal such as an organic lithium compound is used as a polymerization catalyst for producing the diene rubber (A), the metal used as a reference for the catalyst residue amount is an alkali metal such as lithium. When the amount of catalyst residue is within the above range, the tack does not decrease during processing, etc., and the heat resistance of the crosslinked product obtained from the rubber composition of the present invention and the rolling resistance performance of the tire, which will be described later, are improved. . The amount of catalyst residue derived from the polymerization catalyst used for producing the diene rubber (A) is more preferably 0 to 150 ppm, more preferably 0 to 100 ppm in terms of metal. The catalyst residue amount can be measured by using, for example, a polarized Zeeman atomic absorption spectrophotometer.

As a method for adjusting the catalyst residue amount of the diene rubber (A) to such a specific amount, there is a method of purifying the diene rubber (A) and sufficiently removing the catalyst residue. As a purification method, washing with water or warm water, an organic solvent represented by methanol, acetone, or the like, or a supercritical fluid carbon dioxide is preferable. The number of times of washing is preferably 1 to 20 times, more preferably 1 to 10 times, from an economical point of view. The washing temperature is preferably 20-100°C, more preferably 40-90°C. In addition, by removing impurities that inhibit polymerization by distillation or an adsorbent before the polymerization reaction and increasing the purity of the monomers, the necessary amount of the polymerization catalyst can be reduced. The amount of catalyst residue can be reduced. Further, from the same viewpoint as above, the catalyst residue in the rubber composition containing the solid rubber (B) of the present invention, the diene rubber (A) and the filler (C), which will be described later, is 0 to 200 ppm in terms of metal. is preferred, 0 to 150 ppm is more preferred, and 0 to 100 ppm is even more preferred. The catalyst residue in this case includes the catalyst residue derived from the polymerization catalyst used for producing the solid rubber (B), the diene rubber (A) and/or other optional components contained in the rubber composition.

The diene rubber (A) obtained in this manner can be used as it is, or it may be used by reacting the unsaturated bonds contained in the diene rubber (A) with a modifying compound. A product obtained by hydrogenating at least a part of the unsaturated bonds contained in the rubber may be used as the diene rubber (A).

The diene rubber (A) may be used singly or in combination of two or more.

[Rubber composition]
The rubber composition of the present invention contains a diene rubber (A). When the rubber composition contains the diene rubber (A), a rubber composition with excellent properties can be obtained. In particular, when the rubber composition contains a solid rubber (B) and a filler (C), which will be described later, the rubber composition or the crosslinked product of the rubber composition has both wet grip performance and ice grip performance at a high level. , and excellent mechanical properties.

[Solid rubber (B)]
The rubber composition of the present invention may further contain solid rubber (B). The solid rubber (B) used in the present invention refers to a rubber that can be handled in a solid state at 20°C _. Yes, usually selected from at least one of synthetic rubber and natural rubber.

Examples of the solid rubber (B) include styrene-butadiene rubber (hereinafter also referred to as "SBR"), butadiene rubber, isoprene rubber, butyl rubber, halogenated butyl rubber, ethylene-propylene-diene rubber, butadiene-acrylonitrile copolymer rubber, and chloroprene rubber. , synthetic rubbers such as acrylic rubbers, fluororubbers, and urethane rubbers; and natural rubbers. Among these solid rubbers (B), natural rubber, SBR, butadiene rubber and isoprene rubber are preferred, and natural rubber, butadiene rubber and SBR are more preferred. These solid rubbers (B) may be used singly or in combination of two or more.

The Mw of the solid rubber (B) is preferably 80,000 or more, and within the range of 100,000 to 3,000,000, from the viewpoint of sufficiently exhibiting the properties of the resulting rubber composition and crosslinked product. It is more preferable to have

From the viewpoint of using the rubber composition of the present invention as a tread for winter tires (winter tires, studless tires) and all-season tire treads, the glass transition temperature (Tg) obtained by differential thermal analysis of the solid rubber (B) is , -10 ° C. or lower, preferably -20 ° C. or lower, more preferably -30 ° C. or lower, still more preferably -40 ° C. or lower, even more preferably -45 ° C. or lower, particularly preferably -50 ° C. or lower, most preferably -50 ° C. or lower is below -55°C. When the glass transition temperature is within the above range, the flexibility of the rubber composition at low temperatures is improved, and the ice grip performance is improved. Here, the Tg of the solid rubber (B) is the glass transition temperature of the rubber component that substantially constitutes the solid rubber (B). , the glass transition temperature of each of the plurality of rubber components substantially constituting the solid rubber (B) is -10°C or lower. For example, when the rubber components substantially constituting the solid rubber (B) are STR20 (Thai natural rubber) and butadiene rubber, the glass transition temperature of STR20 and butadiene rubber should be -10°C or lower.

As the SBR, general ones used for tire applications can be used. Specifically, those having a styrene content of 0.1 to 70% by mass are preferable, and those having a styrene content of 5 to 60% by mass are more preferable. 5 to 50% by weight is more preferred, 5 to 40% by weight is even more preferred, 5 to 30% by weight is particularly preferred, and 5 to 25% by weight is most preferred. Also, the vinyl content is preferably 0.1 to 80% by mass, more preferably 5 to 70% by mass.

In addition, the vinyl content of SBR in the present specification represents the content of monomer units having a vinyl group among all butadiene-derived units contained in SBR. Similarly below, the vinyl content of the solid rubber (B) represents the content of monomer units actually having a vinyl group with respect to the total amount of monomer units that may have a vinyl group depending on the form of bonding.

The Mw of SBR is preferably 100,000 to 2,500,000, more preferably 150,000 to 2,000,000, still more preferably 150,000 to 1,500,000. When the Mw of SBR is within the above range, the processability of the rubber composition is improved, the wet grip performance of the tire obtained from the rubber composition is improved, and mechanical strength, wear resistance, and steering stability performance are also improved. improves.

Tg determined by differential thermal analysis of SBR is −10° C. or less, preferably −20° C. or less, more preferably −30° C. or less, still more preferably −40° C. or less, still more preferably −45° C. or less, Particularly preferably -50°C or lower, most preferably -55°C or lower. When the glass transition temperature is within the above range, the flexibility of the rubber composition at low temperatures is improved, and the ice grip performance is improved.

SBR is obtained by copolymerizing styrene and butadiene. The method for producing SBR is not limited, and any of emulsion polymerization method, solution polymerization method, gas phase polymerization method and bulk polymerization method can be used. Among these production methods, emulsion polymerization method and solution polymerization method are preferable.

Emulsion-polymerized styrene-butadiene rubber (hereinafter also referred to as E-SBR) can be produced by a conventional emulsion polymerization method. For example, it can be obtained by emulsifying and dispersing predetermined amounts of styrene and butadiene monomers in the presence of an emulsifier, followed by emulsion polymerization with a radical polymerization initiator.

As the emulsifier, for example, a long-chain fatty acid salt or rosinate having 10 or more carbon atoms is used. Specific examples include potassium or sodium salts of fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, oleic acid and stearic acid.

As the dispersion medium, water is usually used, and a water-soluble organic solvent such as methanol or ethanol may be included as long as the stability during polymerization is not impaired.
Examples of radical polymerization initiators include persulfates such as ammonium persulfate and potassium persulfate, organic peroxides, and hydrogen peroxide.

A chain transfer agent can also be used to adjust the molecular weight of the resulting E-SBR. Examples of chain transfer agents include mercaptans such as t-dodecylmercaptan and n-dodecylmercaptan; carbon tetrachloride, thioglycolic acid, diterpene, terpinolene, γ-terpinene, and α-methylstyrene dimer.

The emulsion polymerization temperature can be appropriately selected depending on the type of radical polymerization initiator used, but is usually preferably 0 to 100°C, more preferably 0 to 60°C. The polymerization mode may be either continuous polymerization or batch polymerization. Polymerization reactions can be terminated by the addition of a polymerization terminating agent.

Examples of the polymerization terminator include amine compounds such as isopropylhydroxylamine, diethylhydroxylamine and hydroxylamine; quinone compounds such as hydroquinone and benzoquinone; and sodium nitrite.

After termination of the polymerization reaction, an anti-aging agent may be added as necessary. After stopping the polymerization reaction, unreacted monomers are removed from the obtained latex if necessary, and then salts such as sodium chloride, calcium chloride and potassium chloride are used as coagulants, and if necessary nitric acid, sulfuric acid and the like are added. After the polymer is coagulated while adjusting the pH of the coagulation system to a predetermined value by adding an acid, the polymer can be recovered as crumbs by separating the dispersion medium. E-SBR is obtained by washing the crumb with water, dehydrating it, and drying it with a band dryer or the like. At the time of coagulation, if necessary, latex and extender oil emulsified and dispersed may be mixed in advance and recovered as oil-extended rubber. In the composition of the rubber composition in this specification, the extender oil is not included in the solid rubber (B).

Commercially available E-SBR products include oil-extended styrene-butadiene rubber “JSR1723” manufactured by JSR Corporation.
Solution-polymerized styrene-butadiene rubber (hereinafter also referred to as S-SBR) can be produced by a conventional solution polymerization method. Polymerizes styrene and butadiene.

Examples of solvents include aliphatic hydrocarbons such as n-butane, n-pentane, isopentane, n-hexane, n-heptane and isooctane; alicyclic hydrocarbons such as cyclopentane, cyclohexane and methylcyclopentane; Aromatic hydrocarbons such as toluene can be mentioned. These solvents are usually preferably used within a range in which the monomer concentration is 1 to 50% by mass.

Examples of anionically polymerizable active metals include alkali metals such as lithium, sodium and potassium; alkaline earth metals such as beryllium, magnesium, calcium, strontium and barium; and lanthanoid rare earth metals such as lanthanum and neodymium. Among these active metals, alkali metals and alkaline earth metals are preferred, and alkali metals are more preferred. Furthermore, among alkali metals, organic alkali metal compounds are more preferably used.

Examples of organic alkali metal compounds include organic monolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium and stilbenelithium; - Polyfunctional organolithium compounds such as dilithio-2-ethylcyclohexane and 1,3,5-trilithiobenzene; sodium naphthalene and potassium naphthalene. Among them, an organic lithium compound is preferred, and an organic monolithium compound is more preferred. The amount of the organic alkali metal compound to be used is appropriately determined according to the required molecular weight of S-SBR. The organic alkali metal compound can also be used as an organic alkali metal amide by reacting it with a secondary amine such as dibutylamine, dihexylamine or dibenzylamine.

The polar compound is not particularly limited as long as it is normally used for adjusting the microstructure of the butadiene unit and the distribution in the styrene copolymer chain without deactivating the reaction in the anionic polymerization. ether compounds such as dibutyl ether, tetrahydrofuran and ethylene glycol diethyl ether; tertiary amines such as N,N,N',N'-tetramethylethylenediamine and trimethylamine; alkali metal alkoxides and phosphine compounds.

The temperature of the polymerization reaction is usually -80 to 150°C, preferably 0 to 100°C, more preferably 30 to 90°C. The polymerization mode may be either a batchwise system or a continuous system. In order to improve the random copolymerizability of styrene and butadiene, styrene and butadiene are continuously or intermittently supplied to the reaction solution so that the composition ratio of styrene and butadiene in the polymerization system is within a specific range. is preferred.

The polymerization reaction can be terminated by adding an alcohol such as methanol or isopropanol as a polymerization terminator. The target S-SBR can be recovered by separating the solvent from the polymerization solution after termination of the polymerization reaction by direct drying, steam stripping, or the like. Before removing the solvent, the polymerization solution and the extender oil may be mixed in advance and recovered as an oil-extended rubber.

As the SBR, modified SBR into which a functional group is introduced may be used as long as it does not impair the effects of the present invention. Examples of functional groups include amino groups, alkoxysilyl groups, hydroxyl groups, epoxy groups, and carboxyl groups.

As a method for producing modified SBR, for example, tin tetrachloride, tetrachlorosilane, dimethyldichlorosilane, dimethyldiethoxysilane, tetramethoxysilane, tetraethoxysilane, which can react with the polymerization active terminal, is added before adding the polymerization terminator. Coupling agents such as 3-aminopropyltriethoxysilane, tetraglycidyl-1,3-bisaminomethylcyclohexane, 2,4-tolylene diisocyanate, 4,4′-bis(diethylamino)benzophenone, N-vinylpyrrolidone, etc. Polymerization terminal modifier, or a method of adding other modifiers described in JP-A-2011-132298. In this modified SBR, the position of the polymer to which the functional group is introduced may be the polymer terminal or the side chain of the polymer chain.

Examples of the isoprene rubber include Ziegler catalysts such as titanium tetrahalide-trialkylaluminum, diethylaluminum chloride-cobalt, trialkylaluminum-boron trifluoride-nickel, and diethylaluminum chloride-nickel; Commercially available isoprene rubbers polymerized using lanthanoid rare earth metal catalysts such as aluminum-neodymium organic acid-Lewis acid, or organic alkali metal compounds as in S-SBR can be used. Isoprene rubber polymerized with a Ziegler-based catalyst is preferred because of its high cis content. Also, an isoprene rubber having an ultra-high cis content obtained using a lanthanoid-based rare earth metal catalyst may be used.

The vinyl content of the isoprene rubber is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. When the vinyl content exceeds 50% by mass, the rolling resistance tends to deteriorate. The lower limit of the vinyl content is not particularly limited. Although the glass transition temperature varies depending on the vinyl content, it is preferably -20°C or lower, more preferably -30°C or lower.

The Mw of the isoprene rubber is preferably 90,000 to 2,000,000, more preferably 150,000 to 1,500,000. When Mw is within the above range, workability and mechanical strength are improved.

Part of the isoprene rubber contains a polyfunctional modifier such as tin tetrachloride, silicon tetrachloride, an alkoxysilane having an epoxy group in the molecule, or an amino group, as long as it does not impair the effects of the present invention. It may have a branched structure or a polar functional group by using a modifier such as alkoxysilane.

Examples of the butadiene rubber include Ziegler catalysts such as titanium tetrahalide-trialkylaluminum, diethylaluminum chloride-cobalt, trialkylaluminum-boron trifluoride-nickel, and diethylaluminum chloride-nickel; Commercially available butadiene rubbers polymerized using lanthanoid rare earth metal catalysts such as aluminum-neodymium organic acid-Lewis acid, or organic alkali metal compounds as in S-SBR can be used. Butadiene rubber polymerized with a Ziegler catalyst is preferred because of its high cis content. Also, a butadiene rubber having an ultra-high cis-isomer content (for example, a cis-isomer content of 95% or more) obtained using a lanthanoid-based rare earth metal catalyst may be used.

The vinyl content of the butadiene rubber is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. When the vinyl content exceeds 50% by mass, the rolling resistance (fuel efficiency) and wear resistance tend to deteriorate. The lower limit of the vinyl content is not particularly limited. Although the glass transition temperature varies depending on the vinyl content, it is preferably -40°C or lower, more preferably -50°C or lower.

Mw of the butadiene rubber is preferably 90,000 to 2,000,000, more preferably 150,000 to 1,500,000. When Mw is within the above range, the processability of the rubber composition is improved, and the ice grip performance, wear resistance and steering stability performance of a tire partially using the rubber composition are also improved.

Part of the butadiene rubber contains a polyfunctional modifier such as tin tetrachloride, silicon tetrachloride, an alkoxysilane having an epoxy group in the molecule, or an amino group, as long as it does not impair the effects of the present invention. It may have branched structures or polar functional groups formed by using modifiers such as alkoxysilanes.

In addition to at least one of SBR, isoprene rubber, and butadiene rubber, one or more of butyl rubber, halogenated butyl rubber, ethylene propylene diene rubber, butadiene acrylonitrile copolymer rubber, chloroprene rubber, etc. can be used. . Moreover, the method for producing these is not particularly limited, and commercially available products can be used.

Examples of the natural rubber include TSR (Technically Specified Rubber) such as SMR (Malaysian TSR), SIR (Indonesian TSR), STR (Thai TSR), and RSS (Ribbed Smoked Sheet), which are commonly used in the tire industry. Modified natural rubbers such as natural rubber, high-purity natural rubber, epoxidized natural rubber, hydroxylated natural rubber, hydrogenated natural rubber, and grafted natural rubber can be used. Among them, SMR20, STR20 and RSS#3 are preferable in terms of less variation in quality and availability. These natural rubbers may be used individually by 1 type, and may use 2 or more types together. In the present invention, synthetic rubber and natural rubber may be used together.

When the rubber composition contains a diene rubber (A) and a solid rubber (B), the content of the diene rubber (A) is 0.1 to 50 parts per 100 parts by mass of the solid rubber (B). Parts by mass are preferable, 0.1 to 45 parts by mass are more preferable, 0.5 to 40 parts by mass are more preferable, 1 to 40 parts by mass are even more preferable, 2 to 40 parts by mass are particularly preferable, and 2 to 30 parts by mass are more preferable. parts are more particularly preferred, and 2 to 20 parts by weight are most preferred. When the content of the diene rubber (A) is within the above range, the diene rubber (A) does not bleed out from the solid rubber (B), and a crosslinked product having excellent wet grip and ice grip performance can be obtained. .
When the rubber composition further contains a filler (C), if the content of the diene rubber (A) is within the above range, the dispersibility of the filler (C) in the rubber composition and the resulting crosslinked product It has a high level of wet grip performance and ice grip performance, and also has good mechanical properties.

[Filler (C)]
The rubber composition of the present invention may contain a filler (C). The filler (C) used in the rubber composition of the present invention is not limited, and can be used to improve physical properties such as improved mechanical strength, dry grip performance, wet grip performance, steering stability performance, and steering stability performance of tires partially using the rubber composition. From the viewpoint of improving fuel efficiency performance, at least one selected from carbon black and silica is preferable, an embodiment containing carbon black as a filler (C) is preferable, and an embodiment containing silica as a filler (C) is also preferable. An embodiment containing carbon black and silica as the filler (C) is also preferred.

Examples of carbon black include furnace black, channel black, thermal black, acetylene black, and ketjen black. From the viewpoint of improving the crosslinking speed, improving the mechanical strength of the resulting crosslinked product, and improving the dry grip performance, wet grip performance, steering stability performance, and fuel efficiency performance of tires partially using the rubber composition, these carbon blacks are used. Among them, furnace black is preferred. These carbon blacks may be used singly or in combination of two or more.

The average particle size of the carbon black is preferably 5 nm or more, more preferably 10 nm or more, and still more preferably 10 nm or more, from the viewpoint of improving the dry grip performance, wet grip performance, and fuel efficiency performance of a tire partially using the rubber composition. is 15 nm or more, and preferably 100 nm or less, more preferably 80 nm or less, even more preferably 70 nm or less, and particularly preferably 60 nm or less. The average particle diameter of carbon black can be obtained by measuring the diameter of the particles with a transmission electron microscope and calculating the average value.

Examples of commercial products of the furnace black include Mitsubishi Chemical Co., Ltd. "Diablack" and Tokai Carbon Co., Ltd. "Seist". Commercially available products of acetylene black include, for example, "Denka Black" manufactured by Denki Kagaku Kogyo. Commercially available products of Ketjenblack include, for example, "ECP600JD" manufactured by Lion Corporation.

From the viewpoint of improving wettability and dispersibility to the solid rubber (B), the carbon black is subjected to acid treatment with nitric acid, sulfuric acid, hydrochloric acid, or a mixed acid thereof, or surface oxidation treatment by heat treatment in the presence of air. may be performed. From the viewpoint of improving the mechanical strength of the rubber composition of the present invention and the crosslinked product obtained from this composition, heat treatment may be performed at 2,000 to 3,000° C. in the presence of a graphitization catalyst. Graphitization catalysts include boron, boron oxides (e.g., _{B2O2 , B2O3 , B4O3 , B4O5 ,} etc.), boron oxo acids (e.g., orthoboric acid, metaboric acid, tetraboric acid, etc.) and salts thereof, boron carbides (eg, B ₄ C, B ₆ C, etc.), boron nitride (BN), and other boron compounds are preferably used.

The carbon black can be used after adjusting the particle size by pulverization or the like. For pulverizing carbon black, high-speed rotary pulverizers (hammer mill, pin mill, cage mill), various ball mills (rolling mill, vibration mill, planetary mill), stirring mills (bead mill, attritor, circulation tube type mill, annular mill) are used. etc. can be used.

Examples of silica include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate. Among these silicas, the processability, mechanical strength and wear resistance of the obtained crosslinked product are further improved, and the dry grip performance, wet grip performance, steering stability performance and fuel efficiency performance of tires partially using the rubber composition From the viewpoint of further improving, wet silica is preferable. These silicas may be used individually by 1 type, and may use 2 or more types together.

The average particle size of silica is preferably 0.5 nm or more from the viewpoint of improving the processability of the rubber composition and the dry grip performance, wet grip performance, and fuel efficiency performance of a tire partially using the rubber composition, More preferably 2 nm or more, still more preferably 5 nm or more, particularly preferably 8 nm or more, most preferably 10 nm or more, and preferably 200 nm or less, more preferably 150 nm or less, still more preferably 100 nm or less, and even more preferably 50 nm. Below, it is particularly preferably 30 nm or less, and most preferably 20 nm or less. The average particle size of silica can be obtained by measuring the diameter of particles with a transmission electron microscope and calculating the average value.

Among these carbon black and silica, silica is more preferable as the filler (C) from the viewpoint of improving the rolling resistance performance of the obtained rubber composition and its crosslinked product.
In the present invention, fillers other than silica and carbon black are added for the purpose of improving the mechanical strength of a tire partially using a rubber composition and improving the production cost by blending a filler as an extender. may contain.

Examples of fillers other than silica and carbon black include organic fillers, clay, talc, mica, calcium carbonate, magnesium hydroxide, aluminum hydroxide, barium sulfate, titanium oxide, glass fibers, fibrous fillers, and glass balloons. Inorganic fillers such as can be used. These fillers may be used individually by 1 type, and may use 2 or more types together.

When the rubber composition of the present invention contains a diene rubber (A), a solid rubber (B) and a filler (C), the content of the filler (C) is 20 parts per 100 parts by mass of the solid rubber (B). It is preferably up to 200 parts by mass. When the amount of the filler (C) is within the above range, the dry grip performance, wet grip performance, and fuel economy performance of the tire partially using the rubber composition are improved. From the above-mentioned viewpoint, the amount of the filler (C) with respect to 100 parts by mass of the solid rubber (B) is more preferably 30 parts by mass or more, still more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, and particularly preferably 60 parts by mass or more, and preferably 150 parts by mass or less, more preferably 120 parts by mass or less, still more preferably 100 parts by mass or less, even more preferably 90 parts by mass or less, particularly preferably 80 parts by mass or less, and more Particularly preferably, it is 70 parts by mass or less.

Further, when the rubber composition of the present invention contains a diene rubber (A), a solid rubber (B) and a filler (C), and silica is used as the filler (C), The amount of silica is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, from the viewpoint of improving the dry grip performance, wet grip performance, and fuel efficiency performance of a tire partially using the rubber composition. It is preferably 30 parts by mass or more, more preferably 35 parts by mass or more, particularly preferably 40 parts by mass or more, most preferably 45 parts by mass or more, and preferably 100 parts by mass or less, more preferably 90 parts by mass or less. , more preferably 80 parts by mass or less, even more preferably 70 parts by mass or less, particularly preferably 65 parts by mass or less, even more preferably 60 parts by mass or less, and most preferably 55 parts by mass or less.

Furthermore, when the rubber composition of the present invention contains a diene rubber (A), a solid rubber (B), and a filler (C), and carbon black is used as the filler (C), 100 mass of the solid rubber (B) The amount of carbon black per part is preferably 10 parts by mass or more, more preferably 20 parts by mass, from the viewpoint of improving the dry grip performance, wet grip performance, and fuel efficiency performance of a tire partially using the rubber composition. More preferably 30 parts by mass or more, particularly preferably 40 parts by mass or more, and preferably 120 parts by mass or less, more preferably 100 parts by mass or less, still more preferably 80 parts by mass or less, still more preferably 70 parts by mass or less, particularly preferably 60 parts by mass or less, more particularly preferably 55 parts by mass or less, and most preferably 50 parts by mass or less.

When silica and carbon black are used together, the ratio of silica and carbon black (mass ratio = silica/carbon black) is preferably 1/99 to 99/1, more preferably 10/90 to 90/10, and 30/70. ~80/20 is even more preferred.

[Other ingredients]
When the rubber composition of the present invention contains silica or the like as the filler (C), it is a preferred embodiment to contain a silane coupling agent. Silane coupling agents include, for example, sulfide compounds, mercapto compounds, vinyl compounds, amino compounds, glycidoxy compounds, nitro compounds, and chloro compounds.

Examples of sulfide compounds include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxy silylethyl) tetrasulfide, bis(3-triethoxysilylpropyl) trisulfide, bis(3-trimethoxysilylpropyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(3-trimethoxysilylpropyl) Disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N,N-dimethylthiocarbamoyl Tetrasulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, 3-octanoylthio-1 - propyltriethoxysilane.

Mercapto-based compounds include, for example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane.

Examples of vinyl compounds include vinyltriethoxysilane and vinyltrimethoxysilane.
Examples of amino compounds include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane. Silanes are mentioned.

Examples of glycidoxy-based compounds include γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and γ-glycidoxypropylmethyldimethoxysilane. be done.

Nitro compounds include, for example, 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane.
Examples of chloro-based compounds include 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, and 2-chloroethyltriethoxysilane.
Other compounds include, for example, octyltriethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, hexadecyltrimethoxysilane.

These silane coupling agents may be used individually by 1 type, and may use 2 or more types together. Among these silane coupling agents, silane coupling agents containing sulfur such as sulfide-based compounds and mercapto-based compounds are preferable from the viewpoint of a large reinforcing effect, and bis (3-triethoxysilylpropyl) disulfide, bis (3- Triethoxysilylpropyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane are more preferred.

The silane coupling agent is contained in an amount of preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, and even more preferably 1 to 15 parts by mass based on 100 parts by mass of the filler (C). When the content of the silane coupling agent is within the above range, dispersibility, coupling effect, reinforcing properties and wear resistance are improved.

The rubber composition of the present invention may further contain a vulcanizing agent (D) to crosslink the rubber. Examples of the vulcanizing agent (D) include sulfur and sulfur compounds. Sulfur compounds include, for example, morpholine disulfides and alkylphenol disulfides. These vulcanizing agents (D) may be used singly or in combination of two or more. When the rubber composition of the present invention contains a diene rubber (A) and a solid rubber (B), the vulcanizing agent (D) is 100 mass of the solid rubber (B) from the viewpoint of the mechanical properties of the crosslinked product. 0.1 to 10 parts by mass, preferably 0.5 to 10 parts by mass, and more preferably 0.8 to 5 parts by mass.

When the rubber composition of the present invention contains a vulcanizing agent (D) for cross-linking (vulcanizing) rubber, it may further contain a vulcanization accelerator (E). Examples of the vulcanization accelerator (E) include guanidine-based compounds, sulfenamide-based compounds, thiazole-based compounds, thiuram-based compounds, thiourea-based compounds, dithiocarbamic acid-based compounds, aldehyde-amine-based compounds, and aldehyde-ammonia-based compounds. , imidazoline-based compounds, and xanthate-based compounds. These vulcanization accelerators (E) may be used singly or in combination of two or more. When the rubber composition of the present invention contains a diene rubber (A) and a solid rubber (B), the vulcanization accelerator (E) is usually 0.1 per 100 parts by mass of the solid rubber (B). 15 parts by mass, preferably 0.1 to 10 parts by mass.

For example, when the rubber composition of the present invention contains sulfur, a sulfur compound, etc. as a vulcanizing agent (D) for cross-linking (vulcanizing) rubber, it may further contain a vulcanizing aid (F). good. Examples of the vulcanizing aid (F) include fatty acids such as stearic acid, metal oxides such as zinc oxide, and fatty acid metal salts such as zinc stearate. These vulcanizing aids (F) may be used singly or in combination of two or more. When the rubber composition of the present invention contains a diene rubber (A) and a solid rubber (B), the amount of the vulcanization aid (F) is usually 0.1 per 100 parts by mass of the solid rubber (B). 15 parts by mass, preferably 1 to 10 parts by mass.

The rubber composition may contain a cross-linking agent in addition to the vulcanizing agent. Examples of cross-linking agents include oxygen, organic peroxides, phenolic resins, amino resins, quinones and quinonedioxime derivatives, halogen compounds, aldehyde compounds, alcohol compounds, epoxy compounds, metal halides, organometallic halides, and silanes. compounds and the like. These may be used individually by 1 type, and may use 2 or more types together. When the rubber composition of the present invention contains a diene rubber (A) and a solid rubber (B), the amount of the cross-linking agent is preferably 0.1 to 10 parts per 100 parts by mass of the solid rubber (B). part by mass.

The rubber composition of the present invention is intended to improve processability, fluidity, etc., within a range that does not impair the effects of the present invention. MES (Mild Extracted Solvates), RAE (Residual Aromatic Extracts), process oils such as paraffin oil and naphthenic oil, aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, C9 resins, rosin resins, coumarone/indene resins , a resin component such as a phenolic resin may be contained as a softening agent. When the rubber composition of the present invention contains the process oil as a softening agent and also contains the diene rubber (A) and the solid rubber (B), the content thereof is, from the viewpoint of bleed resistance, It is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 15 parts by mass or less based on 100 parts by mass of the solid rubber (B).

The rubber composition of the present invention may optionally contain an antioxidant, an antioxidant, a wax, a lubricant, and the like for the purpose of improving weather resistance, heat resistance, oxidation resistance, etc., to the extent that the effects of the present invention are not impaired. Light stabilizers, anti-scorch agents, processing aids, coloring agents such as pigments and dyes, flame retardants, antistatic agents, matting agents, antiblocking agents, ultraviolet absorbers, release agents, foaming agents, antibacterial agents, antibacterial agents Additives such as fungicides and fragrances may be contained.

Examples of antioxidants include hindered phenol-based compounds, phosphorus-based compounds, lactone-based compounds, and hydroxyl-based compounds.
Anti-aging agents include, for example, amine-ketone compounds, imidazole compounds, amine compounds, phenol compounds, sulfur compounds and phosphorus compounds. These additives may be used individually by 1 type, and may use 2 or more types together.

[Method for producing rubber composition]
The method for producing the rubber composition of the present invention is not particularly limited as long as the above components can be uniformly mixed. Apparatuses used for the production of rubber compositions include, for example, kneader-ruders, Brabenders, Banbury mixers, tangential or intermeshing internal kneaders such as internal mixers, single-screw extruders, twin-screw extruders, and mixing rolls. , and rollers. The production of the rubber composition can usually be carried out in the temperature range of 50 to 270°C.

The rubber composition of the present invention is preferably used as a crosslinked product (vulcanized rubber) by crosslinking. The conditions and method of vulcanization are not particularly limited, but it is preferable to use a vulcanization mold under the conditions of a vulcanization temperature of 120 to 200° C. and a vulcanization pressure of 0.5 to 20 MPa.

The extraction rate of the diene rubber (A) from the crosslinked product is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less.
The extraction rate can be calculated from the amount of the diene rubber (A) extracted into toluene after immersing 2 g of the crosslinked product in 400 mL of toluene at 23° C. for 48 hours.

[Tire tread and pneumatic tire]
The tire tread of the present invention is a rubber composition containing the rubber composition, typically a diene rubber (A), a solid rubber (B) and a filler (C), or a crosslinked product obtained by crosslinking the rubber composition. is used at least in part, and has sufficient dry grip performance, excellent wet grip performance and ice grip performance, and excellent steering stability performance. The structure of the tire tread of the present invention is not particularly limited, and may be a single layer structure or a multilayer structure. In the case of a multilayer structure, it is preferable to use the rubber composition for the layer that contacts the road surface. .

The pneumatic tire of the present invention is a rubber composition containing the rubber composition, typically a diene rubber (A), a solid rubber (B) and a filler (C), or a crosslinked rubber composition obtained by crosslinking the rubber composition. A pneumatic tire using the above tire tread is particularly preferable. Since the pneumatic tire of the present invention partially uses the rubber composition, it has sufficient dry grip performance, excellent wet grip performance and ice grip performance, and improved steering stability performance. Excellent abrasion resistance. Therefore, the pneumatic tire is suitable as a winter tire, a winter tire such as a studless tire, and an all-season tire.

Tire parts that can use the rubber composition and the crosslinked product of the rubber composition include, for example, tread (cap tread, undertread), sidewall, rubber reinforcing layer for run-flat tires (liner etc.), rim cushion, Bead fillers, bead insulation, bead apex, clinch apex, belts (belts for tires), belt cushions, breakers, breaker cushions, chafers, chafer pads, strip apex, and the like.

[Resin modifier]
Since the diene rubber (A) of the present invention has the above excellent properties, it can also be used as a resin modifier. A resin modifier comprising a diene rubber (A) can be mixed with a resin and used as a resin composition.

The resin is not particularly limited, and for example, thermosetting resins and thermoplastic resins can be used. Examples of thermoplastic resins include olefin-based resins, styrene-based resins, polyphenylene ether-based resins, polycarbonate-based resins, polyamide-based resins, isobutylene-isoprene copolymer rubbers, polyurethane-based thermoplastic elastomers, and the like. These thermoplastic resins can be used singly or in combination of two or more. Moreover, the resin composition may contain various additives as necessary.

The method for preparing the resin composition is not particularly limited, and various methods can be used. For example, when the resin is a thermoplastic resin, for example, a resin modifier comprising a diene rubber (A), a thermoplastic resin, and various additives optionally included are mixed using a mixer such as a Henschel mixer. Further, after this mixing, using a kneader such as a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer, or a roll, a method of producing by melt-kneading under heating conditions, The above resin composition can be prepared. In addition, a resin modifier comprising a diene rubber (A), a thermoplastic resin, and optionally various additives are dissolved in a soluble solvent, and the resin composition is prepared by a method of removing the solvent. can be prepared.

The above resin composition is useful in various applications such as pressure-sensitive adhesives, adhesives, and vibration-damping materials.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

Components used in Examples and Comparative Examples are as follows.
[Diene rubber (A)]
Polymers (A-1) to (A-4) obtained in Production Examples 1 to 4 described later
[Solid rubber (B)]
Natural rubber (NR) STR20 (made in Thailand): manufactured by VON BUNDIT, Tg -62.6°C
Butadiene rubber (BR): BR01 (manufactured by JSR Corporation, high cis type [1,4-cis bond 95%], weight average molecular weight 520,000, Tg -103°C
[Filler (C)]
Carbon black: Diablack I (N220) (manufactured by Mitsubishi Chemical Corporation, average particle size 20 nm)
Silica: ULTRASIL7000GR (manufactured by Evonik Japan Co., Ltd., wet silica, average particle size 14 nm)
[Optional component]
(Silane coupling agent)
SI75 (manufactured by Evonik Japan Co., Ltd.)
(vulcanizing agent)
Sulfur: Myucron OT-20 (Shikoku Chemical Industry Co., Ltd.)
(vulcanization aid)
Stearic acid: Runac S-20 (manufactured by Kao Corporation)
Zinc white: Zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd.)
(Vulcanization accelerator)
Vulcanization accelerator (1): Suncellar NS (Sanshin Chemical Industry Co., Ltd.)
Vulcanization accelerator (2): Noccellar D (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)
(Antiaging agent)
Antiaging agent (1): Nocrac 6C (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)
Antiaging agent (2): Antage RD (Kawaguchi Chemical Industry Co., Ltd.)
(other ingredients)
TDAE: VivaTec500 (manufactured by H&R)
Wax: Suntite S (manufactured by Seiko Chemical Co., Ltd.)

Methods for measuring and calculating physical properties of the diene polymers obtained in the following production examples are as follows.

(Weight average molecular weight, number average molecular weight, and molecular weight distribution)
Using "HLC-8320" manufactured by Tosoh Corporation, the concentration of sample/tetrahydrofuran was adjusted to 5 mg/10 mL and measured. Tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd. was used as the developing solution.
The weight average molecular weight (Mw) and number average molecular weight (Mn) were determined by GPC (gel permeation chromatography) in terms of standard polystyrene, and the molecular weight distribution (Mw/Mn) was calculated from these values. The measuring device and conditions are as follows.
[Measurement device and measurement conditions]
・ Apparatus: GPC apparatus "HLC-8320" manufactured by Tosoh Corporation
・ Separation column: Column “TSKgelSuperHZM-M” manufactured by Tosoh Corporation
・Eluent: Tetrahydrofuran ・Eluent flow rate: 0.7 ml/min
・Sample concentration: 5mg/10ml
・Column temperature: 40°C

(Glass transition temperature (Tg))
A 10 mg sample was placed in an aluminum open pan, an aluminum lid was placed on the pan, and the pan was crimped with a sample sealer. A thermogram was measured by differential scanning calorimetry (DSC) at a heating rate of 10°C/min, and the DSC peak top value was taken as the glass transition temperature (Tg). The measuring equipment and conditions are as follows.
[Measurement device and measurement conditions]
・ Apparatus: Differential scanning calorimeter "DSC6200" manufactured by Seiko Instruments Inc.
・Cooling device: Cooling controller manufactured by Seiko Instruments Inc. ・Detector: Heat flux type
・Sample weight: 10 mg
・Temperature increase rate: 10°C/min
- Cooling condition: After cooling at 10°C/min, the temperature was maintained isothermally at -130°C for 3 minutes, and the temperature was started to rise.
・ Reference container: aluminum ・ Reference weight: 0 mg

(β ₁₂ and β _cp )
A solution prepared by dissolving 50 mg of the diene polymer obtained in the production example in 1 ml of deuterated chloroform (CDCl ₃ ) was measured by 400 MHz ¹ H-NMR at 512 integration times. Based on the integrated values of the following parts of the chart obtained by measurement, β ₁₂ (1,2-bonded butadiene unit mol %) and β _cp (structural unit represented by formula (1)) were calculated according to the following method. mol%) was obtained.
4.65-5.22 ppm part: part A (composite spectrum derived from 1,2 bond and structural unit represented by formula (1))
5.22-5.68 ppm part: part B (composite spectrum of 1,2 and 1,4 bonds)
5.68-5.95 ppm part: Part C (spectrum derived from the structural unit represented by formula (1))
β ₁₂ =[(Integral value of part A−Integral value of part B×2)/2]/[(Integral value of part A−Integral value of part C×2)/2+[Integral value of part C−(Part Integral value of A−Integral value of part C×2)/2]/2+Integral value of part C]×100
β _cp = integral value of portion C/{(integral value of portion A−integral value of portion C×2)/2+[integral value of portion C−(integral value of portion A−integral value of portion C×2)/ 2]/2 + integral value of part C}×100

(Production of diene polymer (A))
Production Example 1: Diene polymer (A-1)
1320 g of cyclohexane as a solvent and 66.4 g of n-butyllithium (1.6 mol/L hexane solution) as a polymerization initiator were placed in a pressure-resistant vessel that had been purged with nitrogen and dried, and the temperature was raised to 50°C. After that, 4.3 g of N,N,N',N'-tetramethylethylenediamine (TMEDA) was charged (0.2 mol per 1 mol of the polymerization initiator), and 1320 g of a previously prepared mixture of butadiene was added. It was added at 12.5 ml/min (feed rate of butadiene to 1 mol of polymerization initiator: 0.9 mol/min) and polymerized for 1 hour. After stopping the polymerization by adding 7.1 g of methanol to the obtained polymerization reaction liquid, the polymerization reaction liquid was washed with 2 L of water. The polymer (A-1) was obtained by separating the polymerization reaction solution after washing from water and drying under reduced pressure at 70° C. for 12 hours. Table 1 shows the physical properties of the obtained polymer.

Production Example 2: Diene polymer (A-2)
1380 g of cyclohexane as a solvent and 109.2 g of n-butyllithium (1.6 mol/L hexane solution) as a polymerization initiator were placed in a pressure vessel that had been purged with nitrogen and dried, and the temperature was raised to 50°C. After that, 13.2 g of tetrahydrofuran (THF) was charged (0.7 mol per 1 mol of the polymerization initiator), and a previously prepared mixture of 1000 g of butadiene was added at 12.5 ml/min (per 1 mol of the polymerization initiator). Butadiene was added at a feed rate of 0.5 mol/min) and polymerized for 1 hour. After stopping the polymerization by adding 10.6 g of methanol to the obtained polymerization reaction liquid, the polymerization reaction liquid was washed with 2 L of water. The polymer (A-2) was obtained by separating the polymerization reaction solution after washing from water and drying under reduced pressure at 70° C. for 12 hours. Table 1 shows the physical properties of the obtained polymer.

Production Example 3: Diene polymer (A-3)
1500 g of cyclohexane as a solvent and 152.9 g of n-butyllithium (1.6 mol/L hexane solution) as a polymerization initiator were placed in a pressure vessel that had been purged with nitrogen and dried, and the temperature was raised to 50.degree. After that, 9.29 g of TMEDA was charged (0.2 mol per 1 mol of the polymerization initiator), and a pre-prepared mixture of 1000 g of butadiene was added at a rate of 12.5 ml/min (butadiene feed per 1 mol of the polymerization initiator). 0.4 mol/min) and polymerized for 1 hour. After stopping the polymerization by adding 14.8 g of methanol to the obtained polymerization reaction liquid, the polymerization reaction liquid was washed with 2 L of water. The polymer (A-3) was obtained by separating the polymerization reaction solution after washing from water and drying under reduced pressure at 70° C. for 12 hours. Table 1 shows the physical properties of the obtained polymer.

Production Example 4: Diene polymer (A-4)
1184 g of hexane as a solvent and 45.2 g of n-butyllithium (1.6 mol/L hexane solution) as a polymerization initiator were placed in a pressure-resistant vessel that had been purged with nitrogen and dried, and the temperature was raised to 40°C. Then, 13.2 g of TMEDA was added (1 mol per 1 mol of the polymerization initiator), and 1184 g of a previously prepared mixture of butadiene was added at 10 ml/min (feed rate of butadiene per 1 mol of polymerization initiator: 1 mol/mol). minutes) and polymerized for 1 hour. After stopping the polymerization by adding 4.8 g of methanol to the obtained polymerization reaction liquid, the polymerization reaction liquid was washed with 2 L of water. After washing, the polymerization reaction solution was separated from water and dried under reduced pressure at 70° C. for 12 hours to obtain a polymer (A-4). Table 1 shows the physical properties of the obtained polymer.

Production Example 5: Diene polymer (A'-5)
1184 g of hexane as a solvent and 45.2 g of n-butyllithium (1.6 mol/L hexane solution) as a polymerization initiator were placed in a pressure-resistant vessel that had been purged with nitrogen and dried, and the temperature was raised to 40°C. Then, 13.2 g of TMEDA was charged (1 mol per 1 mol of the polymerization initiator), and a previously prepared mixture of 1184 g of butadiene was added at 5 ml/min (feed rate of butadiene per 1 mol of the polymerization initiator: 0.5 mol/min) and polymerized for 1 hour. After stopping the polymerization by adding 4.8 g of methanol to the obtained polymerization reaction liquid, the polymerization reaction liquid was washed with 2 L of water. After washing, the polymerization reaction solution was separated from water and dried under reduced pressure at 70° C. for 12 hours to obtain a polymer (A′-5). Table 1 shows the physical properties of the obtained polymer.

Production Example 6: Diene polymer (A'-6)
1000 g of hexane as a solvent and 28.3 g of n-butyllithium (1.6 mol/L hexane solution) as a polymerization initiator were placed in a pressure vessel that had been purged with nitrogen and dried, and the temperature was raised to 50°C. Thereafter, 1000 g of a mixed liquid of butadiene prepared in advance was added at a rate of 12.5 ml/min (feed rate of butadiene to 1 mol of polymerization initiator: 2 mol/min), and polymerization was carried out for 1 hour. After 2.7 g of methanol was added to the obtained polymerization reaction liquid to terminate the polymerization, the polymerization reaction liquid was washed with 2 L of water. After washing, the polymerization reaction solution was separated from water and dried under reduced pressure at 70° C. for 12 hours to obtain a polymer (A′-6). Table 1 shows the physical properties of the obtained polymer.

Examples 1-4 and Comparative Examples 1-3
Polymer (A), solid rubber (B), filler (C), vulcanizing aid, silane coupling agent, anti-aging agent and other components are added according to the blending ratio (parts by mass) shown in Table 2. Each mixture was put into a closed Banbury mixer and kneaded for 6 minutes so that the starting temperature was 60° C. and the resin temperature was 140° C., then taken out of the mixer and cooled to room temperature. Next, this mixture was put into a closed Banbury mixer again, a vulcanizing agent and a vulcanization accelerator were added, and kneaded for 75 seconds so that the starting temperature was 50°C and the final temperature was 100°C, thereby obtaining a rubber composition. .
The obtained rubber composition was press molded (press conditions: 145° C., 70 to 75 minutes) to prepare a crosslinked (vulcanized rubber) sheet (thickness 2 mm), and the storage elasticity was measured according to the following method. modulus, and Tan δ were measured. Table 2 shows the results.

(Ice grip performance)
A test piece with a length of 40 mm and a width of 5 mm was cut out from the crosslinked sheets prepared in Examples and Comparative Examples, and measured using a dynamic viscoelasticity measuring device manufactured by GABO, at a measurement temperature of -20°C, a frequency of 10 Hz, and a static strain of 10%. , the storage modulus (E′) and Tan δ under the condition of dynamic strain of 2% were measured and used as indices of ice grip performance. Table 2 shows absolute values and relative values when the value of Comparative Example 3 is set to 100. The smaller the absolute value of the storage modulus (E′) and the larger the relative value, the better the ice grip performance of the rubber composition. The larger the value, the better the ice grip performance of the rubber composition.
Ice Grip Performance A formula for calculating the relative value of the storage modulus (E') is shown.
Relative value of storage elastic modulus (E') of each example or comparative example = (absolute value of storage elastic modulus (E') of comparative example 3 8.63 MPa) / (storage elastic modulus of each example or comparative example ( E′) absolute value × 100
Ice grip performance A formula for calculating the relative value of Tan δ (-20°C) is shown.
Relative value of Tan δ (−20° C.) in each example or comparative example=(Absolute value of Tan δ (−20° C.) in each example or comparative example)/(Absolute value of Tan δ (−20° C.) in Comparative Example 3 0.44)×100

(wet grip performance)
A test piece with a length of 40 mm and a width of 5 mm was cut out from the crosslinked product sheets prepared in Examples and Comparative Examples, and measured using a dynamic viscoelasticity measuring device manufactured by GABO, at a measurement temperature of 0 ° C., a frequency of 10 Hz, a static strain of 10%, Tan δ was measured under the condition of dynamic strain of 2% and used as an index of wet grip performance. Table 2 shows absolute values and relative values when the value of Comparative Example 3 is set to 100. Incidentally, the larger the numerical value, the better the wet grip performance of the rubber composition.
Wet grip performance A formula for calculating the relative value of Tan δ (0°C) is shown.
Wet grip performance of each example or comparative example Relative value of Tan δ (0 ° C.) = (Absolute value of Tan δ (0 ° C.) of each example or comparative example) / (Absolute value of Tan δ (0 ° C.) of Comparative Example 3 0.31)×100

From Table 2, the crosslinked products obtained from the rubber compositions of Examples 1 to 3 have improved ice grip performance and wet grip performance in a well-balanced manner as compared to the crosslinked products of Comparative Examples 1 to 3. Since Example 4 is superior in ice grip performance as compared with Comparative Example 1, both ice grip performance and wet grip performance are improved in a well-balanced manner. In Comparative Example 1, β _cp was too high, so Tan δ (−20° C.) and Tan δ (0° C.) were good, but the storage modulus (−20° C.) became too high, resulting in poor ice grip performance. there is In Comparative Example 2, β ₁₂ and β _cp are too low, so Tan δ (−20° C.) and Tan δ (0° C.) are not sufficiently improved.
Therefore, it can be seen that the rubber compositions of Examples 1 to 4, which satisfy β _cp /(β ₁₂ -40)≦2, have an excellent balance between ice grip performance and wet grip performance.

The diene rubber (A) of the present invention is not only excellent in processability when producing a rubber composition, but also when a crosslinkable rubber composition is formed by adding a crosslinking agent (vulcanizing agent), the rubber The composition or crosslinked product has both wet grip performance and ice grip performance at a high level, and is also excellent in mechanical properties, so it is useful for tire applications and the like.

Claims (10)

A diene rubber (A) containing a butadiene unit and having a weight average molecular weight of 5,000 to 50,000,
β _{is 12} mol%, and β _cp mol % is the mol% of the structural unit represented by the following formula (1), based on the total butadiene units contained in the diene rubber (A). A rubber composition containing a diene rubber (A), a solid rubber (B), a filler (C), and a vulcanizing agent (D) that satisfies the following (i) to (iii) when
The solid rubber (B) is at least one selected from the group consisting of natural rubber, styrene-butadiene rubber, butadiene rubber, and isoprene rubber,
The filler (C) contains silica,
The vulcanizing agent (D) is at least one selected from the group consisting of sulfur and sulfur compounds,
For 100 parts by mass of the solid rubber (B),
The content of the diene rubber (A) is 2 to 30 parts by mass,
The silica content is 20 parts by mass or more and 100 parts by mass or less,
The content of the vulcanizing agent (D) is 0.1 to 10 parts by mass,
A rubber composition.
(i) β _cp >0
(ii) β ₁₂ >40
(iii) βcp _/ (β12-40 ₎ ≤2

2. The rubber composition according to claim 1, wherein the content of said diene rubber (A) is 2 to 20 parts by mass with respect to 100 parts by mass of said solid rubber (B). 3. The rubber composition according to claim 1, further comprising carbon black as the filler (C), wherein the content of the carbon black with respect to 100 parts by mass of the solid rubber (B) is 10 parts by mass or more and 120 parts by mass or less. . A crosslinked product obtained by crosslinking the rubber composition according to any one of claims 1 to 3 . A tire tread at least partially using the rubber composition according to any one of claims 1 to 3 or the crosslinked product according to claim 4 . A bead filler at least partially using the rubber composition according to any one of claims 1 to 3 or the crosslinked product according to claim 4 . A tire belt at least partially using the rubber composition according to any one of claims 1 to 3 or the crosslinked product according to claim 4 . A pneumatic tire at least partially using the rubber composition according to any one of claims 1 to 3 or the crosslinked product according to claim 4 . The pneumatic tire according to claim 8 , wherein said pneumatic tire is a winter tire or studless tire. 9. The pneumatic tire of claim 8 , wherein said pneumatic tire is an all-season tire.